.box {
    display: flex;
    flex-wrap: wrap;
    height: 800px;
    background-color: white;
    /* align-content: flex-start; */
    /* align-content: flex-end; */
    /* align-content: center; */
    /* align-content: space-between; */
    /* align-content: space-around; */
    align-content: stretch;
}
.box-item {
    width: 200px;
    /* height: 200px; */
    height: auto;
    line-height: 200px;
    vertical-align: middle;
    margin: 5px;
    background-color: #ffd200;
    font-size: 100px;
    color: white;
    text-align: center;
}